In the field of infrared detectors, it is desirable to fabricate infrared detector arrays with tight dimensional control so as to allow the assembly of a multiple number of arrays into a focal plane configuration having a much larger dimension than the individual array dimension. In order to accomplish this end, precision detector array delineation which allows butting of individual detector arrays without any pixel outages at the butting seams, is highly advantageous. To achieve true buttability, the precision and accuracy of detector array delineation must be dimensionally small compared to the size of individual pixels. Typically, pixels are 50 to 100 microns in surface area dimension. Dimensions on this scale require delineation to be achieved to within a few micrometers. It is also highly desirable to develop buttable multiplexer electronics which interconnect with the detector arrays to form large focal plane array assemblies.
Known concepts for buttable multiplexer units, for example, have been proposed by various manufacturers in recent years. Those concepts known to the inventors hereof are commonly referred to as Z-technology concepts and include Grumman Space Systems Division's Z-module concept, Irvine Sensors' HYMOSS concept and Rockwell International's Z-Hy approach. It is believed that none of the aforesaid techniques utilize cleaving of multiplexer electronics or infrared detector arrays to achieve buttability or stackability.
The concept of cleaving has previously been utilized to obtain parallel reflective faces on GaAs semiconductor lasers as described by H.C. Casey, Jr. and M.B. panish in "Heterostructure Lasers", Part B, p.161, A.P. and W.L. Bond, B.G. Cohen, R.C.C. Leite and A. Yariv, Appl. Phys. Lett. 2, 57 (1963). Casey, Jr., et al. describes forming a laser cavity by the use of parallel reflecting surfaces to form a Fabry-Perot interferometer. Such parallel mirrors are readily obtained by cleaving as taught by Bond, et al. As taught by Casey, Jr., et al., GaAs has (110) natural cleavage planes normal to the (100) plane on which epitaxial layers are grown. The wafer with metal contacts can be mounted with wax on a thin flexible metal sheet and small indentations may be scribed near one edge of the wafer with a diamond scriber. Slight flexing will then result in cleavage along (110) planes perpendicular to the surface. Apart from the use in fabricating lasers, neither Casey, Jr. nor Bond, et al. suggest extending the concept of cleaving GaAs for precision delineation of infrared detector arrays on an overlying layer of infrared sensitive material.